TCP/IP四层协议系统浅析 https://www.2cto.com/kf/201802/722776.html
网络协议基础原理篇 https://blog.csdn.net/yonggeit/article/details/79115649
网络协议基础 https://www.bilibili.com/read/cv2766477/
OpenStack网络基础知识:L2,L3是什么 https://cloud.51cto.com/art/201501/464178.htm
linux网络协议栈(五)网络层 (1)L2与L3 https://blog.csdn.net/u010246947/article/details/18224993